LISTXATTR(2) Linux Programmer's Manual LISTXATTR(2)NAME
listxattr, llistxattr, flistxattr - list extended attribute names
SYNOPSIS
#include <sys/types.h>
#include <attr/xattr.h>
ssize_t listxattr(const char *path, char *list, size_t size);
ssize_t llistxattr(const char *path, char *list, size_t size);
ssize_t flistxattr(int fd, char *list, size_t size);
DESCRIPTION
Extended attributes are name:value pairs associated with inodes (files, directories, sym-
bolic links, etc.). They are extensions to the normal attributes which are associated
with all inodes in the system (i.e., the stat(2) data). A complete overview of extended
attributes concepts can be found in attr(5).
listxattr() retrieves the list of extended attribute names associated with the given path
in the filesystem. The retrieved list is placed in list, a caller-allocated buffer whose
size (in bytes) is specified in the argument size. The list is the set of (null-termi-
nated) names, one after the other. Names of extended attributes to which the calling
process does not have access may be omitted from the list. The length of the attribute
name list is returned.
llistxattr() is identical to listxattr(), except in the case of a symbolic link, where the
list of names of extended attributes associated with the link itself is retrieved, not the
file that it refers to.
flistxattr() is identical to listxattr(), only the open file referred to by fd (as
returned by open(2)) is interrogated in place of path.
A single extended attribute name is a simple null-terminated string. The name includes a
namespace prefix; there may be several, disjoint namespaces associated with an individual
inode.
An empty buffer of size zero can be passed into these calls to return the current size of
the list of extended attribute names, which can be used to estimate the size of a buffer
which is sufficiently large to hold the list of names.
Example
The list of names is returned as an unordered array of null-terminated character strings
(attribute names are separated by null bytes ('\0')), like this:
user.name1\0system.name1\0user.name2\0
Filesystems like ext2, ext3 and XFS which implement POSIX ACLs using extended attributes,
might return a list like this:
system.posix_acl_access\0system.posix_acl_default\0
RETURN VALUE
On success, a nonnegative number is returned indicating the size of the extended attribute
name list. On failure, -1 is returned and errno is set appropriately.
ERRORS
ENOTSUP
Extended attributes are not supported by the filesystem, or are disabled.
ERANGE The size of the list buffer is too small to hold the result.
In addition, the errors documented in stat(2) can also occur.
VERSIONS
These system calls have been available on Linux since kernel 2.4; glibc support is pro-
vided since version 2.3.
CONFORMING TO
These system calls are Linux-specific.
SEE ALSOgetfattr(1), setfattr(1), getxattr(2), open(2), removexattr(2), setxattr(2), stat(2),
attr(5), symlink(7)COLOPHON
This page is part of release 3.55 of the Linux man-pages project. A description of the
project, and information about reporting bugs, can be found at
http://www.kernel.org/doc/man-pages/.
Linux 2013-04-09 LISTXATTR(2)